DE8813425U1 - Camshaft drive of an internal combustion engine - Google Patents

Description

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Camshaft drive of an internal combustion engine

■ The invention relates to a camshaft drive

- an internal combustion engine with two V-shaped

Cylinder banks, each with two camshafts, one external

! lying and an inner, of which the outer camshafts are driven directly by the crankshaft ' via a first gear and the inner camshafts by the outer camshafts via second i. gear.

In a known camshaft drive of this type (DE-A 34 21 028), the second gears are arranged in the middle of the cylinder banks. This arrangement requires a relatively large cylinder spacing, which increases the longitudinal extension of the internal combustion engine.

The invention is based on the object of creating a generic camshaft drive in which very small cylinder distances can be realized, so that the length of the internal combustion engine is reduced.

This object is achieved according to the invention in that the second gears are arranged at opposite ends of the camshaft pairs, each between the last cylinder of the respective cylinder bank and the adjacent end of the internal combustion engine.

In internal combustion engines with two V-shaped cylinder banks, two connecting rods are usually mounted next to each other on each crank pin of the crankshaft,

where one connecting rod is connected to a piston in the first cylinder row and the other connecting rod to a piston in the second cylinder row. This results in an axial offset of the cylinders in the first cylinder row compared to the cylinders in the second cylinder row. This axial offset is used in the proposal according to the invention to accommodate the second gears, so that no additional space in the axial direction of the internal combustion engine is required for the second gears. |

Preferably, the first gear is a toothed belt gear I

transmissions, while the two-tone transmissions are chain transmissions. *

However, a chain drive can also be used for the first gear .

gears or for the first and second gears Sj

a gear transmission can be used. 1

An embodiment of the invention is described below with reference to the drawings. It shows:

Fig. 1 is a plan view of a νβ internal combustion engine in a schematic representation, and

Fig. 2 is a front view of the camshaft drive of the . Internal combustion engine of Fig. 1.

In Fig. 1, a νβ internal combustion engine with two cylinder banks 1 and 2 is shown, each containing four cylinders 3 and 4. Reference numeral 5 designates a crankshaft, which has a number corresponding to the number of cylinders in a cylinder bank, i.e. four crank pins 6 in the exemplary embodiment, on each of which two connecting rods 7 and 8 are arranged next to one another, of which the connecting rods 7 are assigned to the pistons (not shown) of the cylinders 3 of the cylinder bank 1 and the connecting rods 8 are assigned to the pistons (not shown) of the cylinders 4 of the cylinder bank 2. This results in - I

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There is an axial offset of the cylinders 3 of the cylinder bank 1 compared to the cylinders 4 of the cylinder bank 2, i.e. the right outer cylinder 3a of the cylinder bank 1 is at a greater distance from the right end 9 of the internal combustion engine than the right outer cylinder 4a of the cylinder bank 2 and conversely the left outer cylinder 4b of the cylinder bank 2 is at a greater distance from the left end 10 of the internal combustion engine than the left outer cylinder 3b of the cylinder bank 1.

Each cylinder bank 1, 2 has an external exhaust camshaft 11 or 12 and an internal intake camshaft 13 or 14, on which cams 15 are seated, which actuate the intake and exhaust valves (not shown). The external exhaust camshafts 11, 12 are driven by means of a toothed belt 15, which extends around a toothed belt pulley 16 on the crankshaft 5 and toothed belt pulleys 17 and 18 on the external exhaust camshafts 11 and 12. The intake camshaft 13 of the first cylinder bank 1 is driven by the exhaust camshaft 11 by a chain 19, which wraps around a sprocket 20 on the exhaust camshaft 11 and a sprocket 21 on the intake camshaft 13. The chain drive 19, 20, 21 is arranged in the space between the last cylinder 3a and the adjacent end 9 of the internal combustion engine. The intake camshaft 14 of the second cylinder bank 2 is driven by the exhaust camshaft 12 by a chain 22 which wraps around a sprocket 23 on the exhaust camshaft 12 and a sprocket 24 on the intake camshaft 14. This chain drive 22, 23, 24 is arranged between the first cylinder 4b of the cylinder bank 2 and the adjacent end 10 of the internal combustion engine, i.e. at the same end as the toothed belt drive 15, 16, 17, 18 for the external exhaust camshafts 11, 12.

In the camshaft drive shown in Figure 1, the chain gears 19, 20, 21 and 22 _and 23, 24 serving to operate the internal intake camshafts 13 and 14 are accommodated in the spaces resulting from the previously described axial offset of the cylinders of one cylinder bank to the cylinders of the other cylinder bank. As a result, no additional space is required in the axial direction for these chain gears, so that the axial length of the internal combustion engine is limited to a minimum, which is given by the distance between adjacent cylinders required for reasons of strength.

The necessary tensioning devices for the toothed belt 15 and the chains 19 and 22 are not shown for the sake of clarity.

Claims (2)

1. Camshaft drive of an internal combustion engine with two V-shaped cylinder banks (1, 2), each of which has two camshafts (11, 13 or 12, 14), one external and one internal, of which the external camshafts (11, 12) are driven directly by the crankshaft (5) via a first gear (15, 16, 17, 18) and the internal camshafts (13, 14) are driven by the external camshafts (11, 12) via second gears (19, 20, 21 or 22, 23, 24), characterized in that the second gears (19, 20, 21 or 22, 23, 24) are arranged at opposite ends of the camshaft pairs (11, 13 or 12, 14) between the last cylinder (3a or 4b) of the respective cylinder bank (1 or 2) and the adjacent end (9 or 10) of the internal combustion engine. 2. Camshaft drive according to claim 1, characterized in that the first gear (15, 16, 17, 18) is a toothed belt gear and the second gears (19, 20, or 22, 23, 24) are chain gears.